Graphical items may be used on a display to show data and information to a viewer. These graphical items may include text, images, and video. Graphical items in the area of computing are well known and have been in use for many years. Recently, showing three dimensional (3D) graphical items on a display has increased in importance in areas such as gaming, modeling and movies.
When displaying graphical items, a system such as a computer uses a processor in combination with memory to display the items on a screen or other display device. Methods for displaying graphical items vary, but typically they rely on a computer interpreting commands to control a graphics processing device that provides graphical items for display. The graphics processing device typically contains custom hardware for this purpose including a processor and memory. In some computer systems the graphics processing device is fully integrated, and in others it is provided as a separate component known as a graphics card.
Graphics processing devices have limits on their processing power, usually quantified in terms of the amount of graphical items that can be displayed on a screen at any given time. This is typically limited by the capabilities of the hardware embodying the graphics processing device, including processors, memory, and communication channels. Additionally, the amount of graphical items able to be displayed on a screen at a given point can be limited by communication limits between the graphics processing device and computer.
In many scenarios that require graphical items be displayed on a screen, a user only focuses on a portion of the screen, and therefore only a portion of the graphical items, an any given time. Meanwhile, other graphical items continue to be displayed on the remaining portions of the screen, which the user is not focused on. This wastes valuable graphics processing device resources to produce graphical items that cannot be fully appreciated by the user because the visual acuity of a human drops dramatically outside those images immediately focused on.